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    So i missed my first year lecture in organic chemistry and am muddling my way though how to draw molecular orbital energy level diagrams. I'm a bit confused with the following diagram (which is also in my textbook)

    My question:
    In the hybridized state, why is there an electron in the unhybridized 2p orbital when it has a higher energy level than the sp2 orbitals? Would it not be more energetically favourable to put the final electron in with a pair and leave the unhybridized orbital empty?

    A fully explained answer would be much appreciated because this same problem is tripping me up with other bonds too.


    You want the system to be in the configuration with the lowest possible energy. This depends on the molecules geometry but in this case sp2 hybridisation is present because it is more energetically favourable than sp3, and there is an electron in the unhybridised p orbital due to something like a π system being present and correlation energy being maximised.

    It's really hard to say without knowing what molecule this is from.
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